Guackman

Here's what I have:
1985 GSL-SE
Stock exhaust
AUxiliary 5th and 6th port not being opened by backpressure. Not wired opened at this time

I tried searching for this, but could not get anything but "The cats are clogged, hollow them out" and I don't think that's the problem or even if I have a problem.

During normal driving everything seems fine. Quite a bit of power and right now by auxiliary ports(5th and 6th) are not wired open. Not as much punch after 4K as when they are wired open though!

Anyway, last night I was driving home late and decided to just run with it a little. Stayed in 4th gear on a stretch of highway for about 10 miles. Had it pretty steady at between 6200 to 6800 RPM, cruising at 100 to 112 MPH.

So I stop as soon as I take my exit off the highway and open the hood. I see a red glow from underneath the heat shield of the exhaust manifold and right up to the connection to the first cat (glowing red right under the O2 sensor as well). I looked under the car and none of the cats were red or anything, just their normal hot selves. The exhaust seemed to coming out the muffler properly and everything. I then drove home through the residential neighborhood. i.e. normal 2 to 4 K RPM stop and go driving. 2 miles max. Look under the hood and the manifold is not glowing anymore. Cooled down quite a bit. Just a lot of pinging noises as it cooled down.

Is this normal after driving it at pretty high RPM for a while? Would I be able to go that fast for that long if the cats were clogged? Would the cats not be red also if they were clogged? Even the first cat was not red!

Any thoughts would be appreciated.

Thanks.

Greg

Directfreak

iTrader: (2)

A 4th gear run at high RPM is the most load you can put on an engine, even more than accelerating. What you saw is normal.

As you drove normally, it cooled down.

On Turbocharged cars, this is more obvious, and many stock TII cars have the problem with the boost creeping because the tiny wastegate can't keep up.



Either way, when the car is running, make sure plenty of exhaust is coming out the tail pipe.

The GSL-SE's have and exhaust backpressure tube that opens your 5th and 6th ports for you. After 17+ years of hydrocarbons, and crap coming out your engine, they get clogged up.

It is not unusual to remove, degrease, and properly clean your 6-port tube as part of a 50,000 mile maintenance. At that time, removing your intake manifold, removing, cleaning and re-inserting your 6 port sleeves is a good idea too. You'll be suprised by the difference in the engine's responsiveness, especially at High-RPM.

Guackman

Thanks for the info.

My current cat does not have the connector for the split air pipe back to the port actuators. That's why they are not working. The ACV is also not injecting any air into my cat because I do not have the split air pipe.

Today I wired the 5th and 6th ports open. As soon as the weather get a little nicer up here, I have the gaskets for the intake manifold and plan on removing it and giving it a good old cleaning. At this time I'll decide if I should get another cat and split air pipe to run this as Mazda intended or maybe an get an RB setup.

Lots of fun! I was just a little curious about the red hot manifold.

Thanks.